Cold weather aerobic activity poses a number of challenges. Not the least of which is the motivation to actually get out the door when it’s windy and twelve degrees. Mastering the delicate dance of selecting the right layers on cold days is crucial. It’s temping overcompensate on cold days, in an attempt to be warm right out of the gate (don’t do that). An ultra light jacket is a key component to any winter runner, snowshoer, or cross country skier’s gear kit.

The photos featured in this post were captured during a lunch run, with temperatures hovering in the low teens. The trail run involved a steep singletrack climb to the top of an abandoned quarry near my home, a route that has become a personal favorite this winter. I wore the Smartwool PhD Ultra Light Jacket over the top of a Merino wool mid-weight base layer. I was dry and comfortable throughout the run. This jacket features strategically positioned hits of Merino wool, which noticeably helped to dump heat and moisture during the steep climbing section of this run. Once at the top of the climb, I remained dry and comfortable while setting up for photos and making my way around the top of the quarry. The mix of lightweight shell and merino makes for a soft feel. No crunchy shell feeling here. I forgot I was even wearing the thing. Smartwool included much appreciated touches, like Merino wool around the neck and splashes of color on the neck and sleeve. The jacket quickly and easily packs into its own chest pocket, making it a great option as a just-in-case travel jacket.


I’ve relied on many Smartwool products over the years, and this is another well-designed piece of gear. This isn’t going to be the jacket you reach for on your nastiest, wettest outings, but if you want an incredibly comfortable, lighweight, and packable jacket for cold, windy days that might include a little moisture, it’s hard to beat the Smartwool PhD Ultra Light Jacket.


  • Super-light shell fabric with DWR coating provides wind and weather protection
  • Body mapped mesh venting
  • Packs completely into chest pocket for easy storage
  • Knit in Vietnam: Shell – 100% Nylon; Trim – 54% Merino Wool, 46% Polyester (Exclusive of Decoration)
  • Garment Weight: 134 g = 4.7 oz
Smartwool Men's PhD Ultra Light Sport Jacket
Smartwool Men's PhD Ultra Light Sport Jacket
Mitch Kline in the Smartwool Men's PhD Ultra Light Sport Jacket, Feb 20, 2018, Castle Rock, CO
Smartwool Men's PhD Ultra Light Sport Jacket
Mitch Kline, Feb 20, 2018, Castle Rock, CO

All photos by Mitch Kline





MSRP: $115